Predictors for improvement of problem-solving during cognitive remediation for patients with Schizophrenia.

Cognitive remediation is a promising pathway for ameliorating cognitive impairment of patients with schizophrenia. Here, we investigate predictors of improvement in problem-solving ability for two different types of cognitive remediation - specific problem-solving training and training of basic cognition. For this purpose we conducted a re-analysis of a randomized controlled trial comparing these two training approaches. The main outcome measure was improvement in problem-solving performance. Correlational analyses were used to assess the contribution of clinical, cognitive and training-related predictors. In the problem-solving training group, impaired pre-training planning ability was associated with stronger improvement. In contrast, in the basic cognition training group antipsychotic medication dose emerged as a negative predictor. These results demonstrate that predictors for successful cognitive remediation depend on the specific intervention. Furthermore, our results suggest that at least in the planning domain patients with impaired performance benefit particularly from a specific intervention.

Temporal variability and spatial diffusion of the N2 event-related potential in high-functioning patients with schizophrenia.

Recent theories of schizophrenia have proposed a fundamental instability of information processing on a neurophysiological level, which can be measured as an increase in latency variability of event-related potentials (ERPs). If this reflects a fundamental deficit of the schizophrenic illness, it should also occur in high-functioning patients. These patients have also been observed to show a more diffuse activation pattern in neuroimaging studies, which is thought to reflect compensatory processes to maintain task performance. In the present study we investigated temporal variability and spatial diffusion of the visual N2 component in a group of high-functioning patients with preserved cognitive performance. 28 patients with schizophrenia and 28 control participants matched for gender, age and education participated in the study. Subjects performed a visual Go/Nogo task, while event-related potentials were obtained. Trial-to-trial latency variability was calculated with a Wavelet-based method. Patients with schizophrenia showed a robust increase in N2 latency variability at electrodes Fz and Cz in all task conditions. Regarding spatial distribution healthy participants showed a focused fronto-central N2 peak. In contrast, patients with schizophrenia showed a more diffuse pattern and additional negative peaks over lateral electrodes in the Nogo condition. These results clearly show that even in high-functioning patients with schizophrenia a higher temporal variability of ERPs can be observed. This provides support for temporal instability of information processing as a fundamental deficit associated with schizophrenia. The more diffuse scalp distribution might reflect processes that compensate for this instability when cognitive control is required.

Planning and problem-solving training for patients with schizophrenia: a randomized controlled trial.

BACKGROUND: The purpose of this study was to assess whether planning and problem-solving training is more effective in improving functional capacity in patients with schizophrenia than a training program addressing basic cognitive functions. METHODS: Eighty-nine patients with schizophrenia were randomly assigned either to a computer assisted training of planning and problem-solving or a training of basic cognition. Outcome variables included planning and problem-solving ability as well as functional capacity, which represents a proxy measure for functional outcome. RESULTS: Planning and problem-solving training improved one measure of planning and problem-solving more strongly than basic cognition training, while two other measures of planning did not show a differential effect. Participants in both groups improved over time in functional capacity. There was no differential effect of the interventions on functional capacity. CONCLUSION: A differential effect of targeting specific cognitive functions on functional capacity could not be established. Small differences on cognitive outcome variables indicate a potential for differential effects. This will have to be addressed in further research including longer treatment programs and other settings. TRIAL REGISTRATION: ClinicalTrials.gov NCT00507988.

The Plan-a-Day approach to measuring planning ability in patients with schizophrenia.

Deficits in executive functioning are closely related to the level of everyday functioning in patients with schizophrenia. However, many existing neuropsychological measures are limited in their ability to predict functional outcome. To contribute towards closing this gap, we developed a computer-based test of planning ability ("Plan-a-Day") that requires participants to create daily activity schedules in a simulated work setting. Eighty patients diagnosed with schizophrenia were tested with Plan-a-Day and a battery of cognitive ability tests. Plan-a-Day showed satisfactory psychometric properties in terms of consistency, reliability, and construct validity. Compared to other neuropsychological tests used in this study, it also demonstrated incremental validity with regard to the Global Assessment of Functioning. The Plan-a-Day approach, therefore, seems to represent a valid alternative for measuring planning ability in patients with executive function deficits, occupying a middle ground between traditional neuropsychological tests and real-life assessments.

Intra-individual variability in high-functioning patients with schizophrenia.

Intra-individual variability of reaction times (IIV) can be employed as a measure of the stability of information processing, which has been proposed to be fundamentally disturbed in schizophrenia. However, the theoretical and clinical significance of IIV is not clear, in part because it has previously been investigated in subject groups with generalized cognitive impairment. Therefore, the purpose of the study was to assess IIV in high-functioning patients with schizophrenia and relatively preserved cognitive performance. 28 high-functioning patients with schizophrenia and 28 controls performed a Go/Nogo task and a Continuous Performance Test. In contrast to average measures of task performance, IIV differentiated consistently and with large effect size between groups. Modelling with an Ex-Gaussian distribution revealed that patients have a higher proportion of slow responses reflected by an increased tau parameter. The tau parameter was correlated with work capability in the sample with schizophrenia. In conclusion, IIV is an easily obtained measure, which is highly sensitive to fundamental cognitive deficits not directly visible in a high-functioning patient group. The response pattern with more exceedingly slow reactions could reflect a core deficit in the stability of information processing. The relationship with work capability suggests investigation of IIV as a clinical measure.